Hormonal IUD for Endometriosis: How It Works and How Well It Treats Symptoms

Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus, causing inflammation, scar tissue, and pain. The World Health Organization (WHO) estimates it affects about 10% of women and girls of reproductive age worldwide, roughly 190 million people, with symptoms ranging from severe menstrual cramps and chronic pelvic pain to infertility and bowel or urinary problems.

What the hormonal IUD does inside the body

The levonorgestrel-releasing intrauterine system (LNG-IUS), sold under the brand name Mirena among others, is a small T-shaped device placed in the uterus. According to a guideline-comparison review published on PubMed Central (PMC), it releases levonorgestrel — a synthetic progestin — directly into the uterine cavity for about five years. The hormone causes atrophy of the glandular tissue, transforms the stroma, slows cell proliferation, and increases cell death (apoptosis) in endometrial tissue.

WHO lists hormonal IUDs among progestin-delivery options used to manage endometriosis symptoms, alongside combined hormonal contraceptives, other progestins, and NSAIDs for pain. WHO states plainly that none of these treatments cures the disease; they are intended to reduce symptom severity.

How effective is it, according to the evidence

A retrospective study published in the journal Medicine (Baltimore) in March 2022, covering 263 patients treated between January 2008 and April 2015, compared 94 patients who received an LNG-IUS after endometriosis surgery with 169 who did not. At the one-year mark, average non-cyclic pelvic/back pain scores fell from 4.0 to 0.6, dysmenorrhea (period pain) scores fell from 6.5 to 0.8, and dyspareunia/dyschezia (pain during sex or bowel movements) scores fell from 4.1 to 1.3, on a 0–10 scale. The study reported these improvements were sustained through 10 years of follow-up in patients who continued treatment, and that 91.5% of the LNG-IUS group remained on the device for more than five years, compared with 21.9% in the comparison group.

A separate summary in Contemporary OB/GYN of a Cochrane systematic review covering three randomized controlled trials found that women who had an LNG-IUD inserted after endometriosis surgery had a statistically significant reduction in the recurrence of painful periods compared with women managed without the device (risk ratio 0.22). Treatment satisfaction trended higher with the IUD, though that difference did not reach statistical significance, and the review's authors said more well-designed trials were needed to confirm the results.

The PMC guideline review also cites the American College of Obstetricians and Gynecologists (ACOG) as finding the LNG-IUS similarly effective as GnRH agonist drugs for reducing endometriosis-related pelvic pain, and notes it is classified as a second-line treatment — generally considered after first-line options such as progestin pills or combined oral contraceptives, or used as maintenance therapy after surgery to prevent pain from returning.

Practical steps for considering a hormonal IUD

1. Confirm an endometriosis diagnosis or clinical suspicion with a gynecologist, since treatment choice depends on disease severity and individual symptoms, per WHO guidance.
2. Discuss first-line options (progestin pills, combined hormonal contraceptives, NSAIDs) with a clinician, since guidelines summarized in the PMC review generally place LNG-IUS as a second-line or post-surgical maintenance option.
3. If surgery for endometriosis is planned, ask whether placing an LNG-IUS afterward is appropriate, since the Cochrane-reviewed trials specifically studied post-surgical insertion to prevent pain recurrence.
4. Expect an adjustment period: the long-term study in Medicine (Baltimore) reported vaginal spotting in 64% of LNG-IUS users and leukorrhea (vaginal discharge) in 29.1% initially, with these effects diminishing after about five years.
5. Plan for device replacement roughly every five years, as cited in the PMC guideline review, and discuss with a clinician whether continued use remains appropriate at each interval.

Side effects and limits

The Medicine (Baltimore) study found that, unlike oral hormonal medications, the LNG-IUS group reported no systemic side effects such as mood changes or nausea, with adverse effects largely limited to local bleeding changes such as spotting and leukorrhea, which diminished after about five years of use.

Regulatory and access context in Brazil

In Brazil, the Conselho Federal de Farmácia (CFF, the Federal Pharmacy Council) reported on 16 June 2025 that the National Commission for the Incorporation of Technologies in the public health system (Conitec) had issued a favorable decision to incorporate the Mirena hormonal IUD into the public Sistema Único de Saúde (SUS) specifically as an endometriosis treatment option, with the decision published in the Official Union Gazette. Under that decision, the public system had up to 180 days from publication to make the device available, aimed at patients who cannot use oral contraceptives or have not responded to other conventional therapies.